1. Field of the Invention
The invention relates to the detection of deception by measuring brain activity which is associated with acts of deception.
2. Description of the Related Art
Deception, the conscious and intentional misleading of another to accept as true or valid what is actually false or invalid, is an unfortunate, but common human practice with substantial societal costs. For example, according to U.S. government statistics for the years 1999-2002, civil litigation consumed approximately $100 billion annually in attorney fees as both individuals and corporations fought in the courts to resolve disputes that could, in many instances, be decided with reliable deception detection. Government expenditures and lost productivity add even more to the societal cost of civil litigation. Similarly, fraud is estimated to cost the insurance industry $80 billion annually, but reliable deception detection could both reduce insurance premiums and speed claim processing for legitimate claimants. In commerce, industrial espionage and the theft of trade secrets result in untold losses in proprietary confidential information which could be better protected by reliable employee screening. Finally, in the defense and intelligence communities, there is an enormous need to safeguard secret information and, therefore, a need for reliable detection of deception during security clearances and investigations.
The search for an accurate lie detector has a long and colorful history, ranging from the ancient Chinese practice of putting rice in the mouth of suspected liars to the quasi-scientific techniques of polygraph and voice stress analysis (see, e.g., Furedy (1986)). The development of equipment to measure psycho-physiologic functions enabled investigators in the late 19th century to study the peripheral physiologic changes that were associated with deception. This led to the development of more sophisticated peripheral measuring techniques and data analysis, including the polygraph (Yankee (1995)).
Polygraph devices examine differences in peripheral autonomic responses to relevant versus irrelevant questions. For example, current polygraph devices record changes in skin conductance response (SCR), blood pressure, respiration and peripheral vasomotor activity. Whenever a greater autonomic response is recorded after a relevant questions versus an irrelevant question, this data is interpreted as indicative that the subject is being deceptive (see, e.g., Furedy (1986)).
Polygraph devices have several significant limitations. For example, subjects can learn to control some autonomic responses and, thereby, circumvent the ability of the test to detect deception. Conversely, anxiety associated with the test or questions can lead to autonomic responses associated with deception irrespective of the truthfulness of the subject's answers. Polygraph interpretation and testing procedures are also subjective. For example, there is little consensus amongst polygraph examiners regarding the types of questions to ask, and the interpretation of the results can be highly subjective. More fundamentally, polygraph devices do not directly measure any mental activity associated with deception but, rather, measure non-specific peripheral changes in the arousal of the test subject. Not surprisingly, the substantive predictive value of the polygraph has been found to be poor in many screening and investigative situations, and scientific evidence regarding the polygraph's validity is significantly lacking.
Various other techniques have been investigated to predict deception, which also use peripheral measures of autonomic activity. These techniques include measures of papillary size response to visual stimuli that are related to a mock crime scene (Lubow and Fein (1996)), voice analysis, observations of facial and hand movement (Ekman et al. (1991)), observations of verbal cues (Sporer (1997)), hypnosis (Sheehan and Statham (1988)), and high-definition thermal imaging of periorbital changes (Pavlidis et al. (2002)). One of the few methods that actually measures brain activity involves examining the amplitude of the P300 component of event-related brain potentials (Farwell and Donchin (1991); see also U.S. Pat. Nos. 4,941,477, 5,363,858, 5,406,956, and 5,467,777).
More recently, brain imaging techniques have been used to investigate brain activity associated with various mental tasks non-invasively (see, e.g., Ogawa et al. (1990)). For example, Shastri et al. (2000) disclosed the simultaneous use of fMRI and SCR measurements, and noted the potential to reveal relationships between psychological states and patterns of brain activity. However, Shastri et al. did not attempt to measure deception. Rather, they investigated brain activity in response to an auditory stimulus consisting an aggravating clicking sound (10 Hz frequency). Critchley et al. (2000) also measured SCR during fMRI. In their experiments, fMRI was performed in the context of “sympathetic arousal” and “risk-taking behavior” in which subjects picked playing cards and won or lost money based on their choices. Again, however, Critchley et al. did not attempt to detect deception. Other researchers using fMRI and positron emission tomography (PET) have successfully delineated brain activity involved in response inhibition (e.g., “Go/No-Go” tasks) (Elliott et al. (2000), divided attention (Pardo et al. (1991); George et al. (1997); Bush et al. (1998)), anxiety (Rauch and Savage (1997); Lorberbaum et al. (1999)), emotion-related learning with reward and punishment (O'Doherty et al. (2001)), and cognitive breakthrough differentiating components of cognitive control such as performance monitoring (MacDonald et al. (2000)).
The present invention addresses the need for reliable detection of deception by specifically identifying the brain regions involved in deception in an individual, and measuring brain activity associated with potentially deceptive states or responses. By measuring brain activity as opposed to peripheral measures of autonomic or sympathetic responses, the present invention avoids the drawbacks of the prior art, and provides a reliable, objective means of detecting deception. Moreover, because the present invention measures brain activity which is inherent in and necessary to the process of deception, it provides a means of detecting deception which cannot be circumvented by trained, skillful or remorseless liars.